JP7606082B2 - Method for manufacturing wavelength conversion member and wavelength conversion member - Google Patents

Description

This disclosure relates to a method for manufacturing a wavelength conversion member and a wavelength conversion member.

In recent years, white light illumination using light sources such as light-emitting diodes and laser diodes has come into use. The white light of this white light illumination is obtained, for example, by converting the wavelength of blue light emitted by a light-emitting diode using a wavelength conversion material. Patent Document 1 discloses a sintered body in which YAG phosphor particles are dispersed in an alumina ceramic matrix as a wavelength conversion material.

JP 2016-204563 A

Such a sintered body containing phosphor particles is used, for example, in an optical component that converts the light incident from a light incident surface into light having a different wavelength from the incident light and emits it from a light exit surface, and in this case, the surface other than the light incident surface and the light exit surface is covered with a reflecting member so that the light can be efficiently wavelength-converted. Note that in this specification, the wavelength conversion member means a member containing a sintered body, and may be a single sintered body or may include a sintered body and other members such as a reflecting member.
However, in recent years, as wavelength conversion members have come to be widely used for various applications, there has been a demand for improving the light confinement on surfaces other than the light entrance surface and the light exit surface.
Therefore, an object of the present disclosure is to provide a manufacturing method for a wavelength conversion member that can produce a sintered body with improved light confinement on surfaces other than the light entrance surface and light exit surface, and a wavelength conversion member.

In order to solve the above problems, the method for producing a wavelength conversion member according to the present disclosure includes:
A method for producing a wavelength conversion member including a sintered body having a light incident surface, a light exit surface, and a light reflecting surface that is different from the light incident surface and the light exit surface, comprising:
a sintered body preparation step of preparing a sintered body containing inorganic particles and phosphor particles;
a recess forming step of treating the sintered body with acid to form a plurality of recesses on a light reflecting surface of the sintered body;
Includes.

The method for producing a wavelength conversion member according to the present disclosure configured as described above includes the steps of preparing a sintered body containing inorganic particles and phosphor particles, and treating the sintered body with acid to form multiple recesses on the light reflecting surface of the sintered body, so that a sintered body with improved light confinement on surfaces other than the light entrance surface and light exit surface can be produced, and a wavelength conversion member including the sintered body can be produced.

1 is a flow chart of a manufacturing method according to a first embodiment of the present invention. 4 is a flow chart of a sintered body preparation process in the manufacturing method of embodiment 1. 2 is a cross-sectional view of a sintered body prepared in the manufacturing method of embodiment 1. FIG. 4 is a cross-sectional view of a sintered body having a recess formed therein in the manufacturing method of embodiment 1. FIG 4 is a cross-sectional view showing a state in which a sintered body having a recess formed therein is surrounded by a reflecting member in the manufacturing method of the first embodiment. FIG. 4 is a cross-sectional view of a wavelength conversion member assembly obtained by processing a reflecting member including a sintered body having recesses formed therein in the manufacturing method of embodiment 1. FIG. FIG. 3E is a plan view of the wavelength conversion member assembly of FIG. 3D. 10 is a plan view of a wavelength conversion member after the wavelength conversion member assembly is divided into individual pieces in the manufacturing method of embodiment 1. FIG. 4A to 4C are schematic diagrams of application examples of a wavelength conversion member produced by the manufacturing method of embodiment 1. FIG. 11 is a simplified schematic cross-sectional view for explaining a method for evaluating the distribution of phosphor particles in a sintered body. FIG. 11 is a cross-sectional view of a sintered body prepared in the manufacturing method of embodiment 2. FIG. 11 is a cross-sectional view of a sintered body having a recess formed therein in the manufacturing method of embodiment 2. FIG. 11 is a cross-sectional view of a sintered body after a portion of a formed recess is removed in a manufacturing method of embodiment 2. 11 is a cross-sectional view of a sintered body after the protrusions of the sintered body are singulated in the manufacturing method of embodiment 2. FIG. 13 is a cross-sectional view of a prepared reflective member in a manufacturing method according to a second embodiment. FIG. 13 is a cross-sectional view of the prepared reflective member after an individualized sintered body is inserted into a through hole in the reflective member in the manufacturing method of embodiment 2. FIG. 13 is a cross-sectional view of the manufacturing method of the second embodiment after glass is provided on the sintered body inserted into the through hole. FIG. FIG. 11 is a cross-sectional view of the glass after the surface of the glass is polished in the manufacturing method of the embodiment 2. 11A to 11C are schematic diagrams of application examples of a wavelength conversion member produced by the production method of embodiment 2. 13 is a flow chart of a manufacturing method according to a third embodiment of the present invention. 11 is a cross-sectional view of a phosphor ceramic plate having a mask formed on its upper surface and a protective film formed on its lower surface in a manufacturing method according to a third embodiment. FIG. FIG. 6B is a plan view of the phosphor ceramic plate of FIG. 6A. 13 is a cross-sectional view of a phosphor ceramic plate having recesses formed therein in a manufacturing method according to a third embodiment. FIG. 13 is a cross-sectional view showing a state in which a reflective film is formed on the entire lower surface of a phosphor ceramic plate in the manufacturing method of embodiment 3. FIG. 13 is a cross-sectional view showing a state where a support body is provided to support the phosphor ceramic plate from the lower surface side in the manufacturing method of the third embodiment. FIG. 13A to 13C are schematic diagrams of application examples of a wavelength conversion member produced by the manufacturing method of embodiment 3. 13 is a cross-sectional photograph of a sintered body produced in the same manner as in the experimental example, when a reflecting member is formed on the light reflecting surface of the sintered body. 7B is a cross-sectional photograph of the sintered body from which the reflective member has been removed, FIG. 7A. 13 is a cross-sectional photograph of a sintered body produced in the same manner as in the comparative example, when a reflective member is formed on the light-reflecting surface of the sintered body.

The method for manufacturing a wavelength conversion member according to the present disclosure was developed by discovering that acid-treating a sintered body containing inorganic particles and phosphor particles improves light confinement on the acid-treated surface, and includes a sintered body preparation step of preparing a sintered body containing at least inorganic particles and phosphor particles, and a recess formation step.
Here, the recess forming step is a step of acid-treating the surface of the prepared sintered body to form multiple recesses on the light-reflecting surface of the sintered body. More specifically, by acid-treating the surface of the sintered body, the phosphor particles exposed on the light-reflecting surface of the sintered body are removed, and multiple recesses are formed on the light-reflecting surface of the sintered body formed by the remaining inorganic particles. By forming multiple recesses on the light-reflecting surface of the sintered body as described above, it is possible to improve the confinement of light on the light-reflecting surface. This is thought to be due to the refractive index difference between the inorganic particles on the light-reflecting surface and the voids of the recesses. It is also thought to be due to a decrease in the phosphor particles exposed on the light-reflecting surface.

Furthermore, the method for producing a wavelength conversion member according to the present disclosure may include any one of the following steps as necessary to suppress light confinement on the surfaces used as the light incident surface and the light exit surface of the sintered body.
(a) a recess removing step of removing the recesses from the surfaces to be used as the light incident surface and the light emitting surface, among the surfaces on which the recesses have been formed by the acid treatment after the recess forming step;
(b) A step of forming a mask on the surfaces to be used as the light incident surface and the light emitting surface, prior to the recess forming step, so as to prevent the surfaces from being exposed to the acid treatment.

According to the manufacturing method of the wavelength conversion member of the present disclosure, the surface of the sintered body, excluding the light incident surface and the light exit surface, can be made into a light reflecting surface with improved light confinement. Since the surface of the sintered body, excluding the light incident surface and the light exit surface, of the sintered body produced as described above is a light reflecting surface with improved light confinement, it is possible to reduce light leaking from the surface excluding the light incident surface and the light exit surface, and the light incident from the light incident surface can be efficiently wavelength converted and emitted from the light exit surface.
The light incident surface and the light emitting surface of the sintered body to be produced may be different surfaces or may be the same surface.

In addition, in the manufacturing method of the wavelength conversion member of the embodiment, by further including a reflecting member arrangement step of exposing the light entrance surface and the light exit surface of the sintered body and providing a reflecting member that contacts and covers the light reflection surface on which the multiple recesses are formed, a wavelength conversion member including a sintered body and a reflecting member can be manufactured. This wavelength conversion member including a sintered body and a reflecting member can not only confine light in the light reflection surface of the sintered body, but also increase the light reflectance at the interface between the sintered body and the reflecting member, thereby suppressing light bleeding around the light exit surface of the sintered body. This makes it possible to increase the luminance difference between the light exit surface of the sintered body and the outside of the light exit surface, in other words, to clearly define the boundary between the light exit surface of the sintered body and the reflecting member surrounding the light exit surface, and thus to manufacture a wavelength conversion member with excellent visibility.

Hereinafter, the method for producing a wavelength conversion member according to the embodiment will be described in detail using more specific examples with reference to the drawings.
The manufacturing method of the wavelength conversion member of the first to third embodiments described below includes a reflective member arrangement step, but the reflective member arrangement step is an optional step that is provided as necessary. That is, as described above, the sintered body having a plurality of recesses formed on the light reflecting surface produced by the manufacturing method of the wavelength conversion member of the embodiment can improve the light confinement on the light reflecting surface, and therefore can improve the light confinement without including a reflective member that contacts and covers the light reflecting surface, and can be used as a wavelength conversion member without including a reflective member that covers the light reflecting surface.
The following embodiments 1 to 3 embody the technical ideas of the above-mentioned embodiments, but do not limit the present invention. In the following description, the same names and symbols indicate the same or similar components, and duplicate descriptions may be omitted as appropriate. The sizes and positional relationships of the components shown in each drawing may be exaggerated to clarify the description.

EMBODIMENT 1
As shown in FIG. 1, the method for manufacturing wavelength conversion member 1 of embodiment 1 includes a sintered body preparing step S1, a recess forming step S2, and a reflecting member arranging step S3.

1. Sintered body preparation step S1
As shown in FIG. 2, the sintered body preparation step S1 includes a weighing step S11, a mixing step S12, a molding step S13, a sintering step S14, and a processing step S15.
Each step will now be described in detail.

(1-1) Weighing step S11
Here, inorganic particles and phosphor particles are prepared, and the inorganic particles and phosphor particles are weighed in a predetermined amount. The preparation of phosphor particles includes not only the preparation of phosphor particles themselves, but also the preparation of materials that are the raw materials of phosphor particles. For example, when preparing YAG phosphor particles, aluminum oxide, yttrium oxide, and cerium oxide particles may be prepared.

The phosphor particles are excited by incident light and emit light with a longer wavelength than the incident light, and the inorganic particles support the phosphor particles after sintering.

The phosphor particles are prepared by using one or more phosphor particles selected from, for example, a cerium-activated YAG (Yttrium Aluminum Garnet) phosphor, a nitrogen-containing calcium aluminosilicate (CaO-Al ₂ O ₃ -SiO ₂ ) phosphor activated with europium and/or chromium, a silicate ((Sr,Ba) ₂ SiO ₄ ) phosphor activated with europium, an α-sialon phosphor, a β-sialon phosphor, and the like. As the phosphor particles, it is preferable to use a material that is relatively heat-resistant and less likely to deteriorate due to excitation light, and a suitable material is, for example, a YAG phosphor. Here, the YAG phosphor includes, for example, one in which at least a part of Y is replaced with Tb, or one in which at least a part of Y is replaced with Lu. The YAG phosphor may also include Gd, Ga, or the like in its composition.

The particle size of the phosphor particles to be prepared is preferably, for example, in the range of 0.1 μm or more and 30 μm or less, and more preferably in the range of 1 μm or more and 5 μm or less. By setting the particle size in this range, it is possible to further improve the light confinement on the surface of the sintered body 11 after the acid treatment. In this case, inorganic particles with a sintering temperature lower than the sintering temperature of the phosphor particles are used as the inorganic particles. This allows the inorganic particles to be sintered while reducing the thermal deterioration of the phosphor particles.

In addition, inorganic particles made of one or more kinds selected from oxides such as aluminum oxide or yttrium oxide, nitrides, etc. are prepared as inorganic particles. It is preferable to use a material with a thermal expansion coefficient close to that of the phosphor particles or a material with low light absorption as the inorganic particles, and a suitable material is, for example, aluminum oxide.
The particle size of the inorganic particles to be prepared is preferably smaller than that of the phosphor particles, for example, in the range of 0.01 μm or more and 1 μm or less, more preferably 0.3 μm or more and 0.6 μm or less. In addition to the selection of the material of the inorganic particles, by selecting particles smaller than the particle size of the phosphor particles, the sintering temperature of the inorganic particles can be set to a lower sintering temperature than that of the phosphor particles. This allows the inorganic particles to be sintered while suppressing the deterioration of the phosphor particles due to heat and abnormal grain growth. In addition, if the particle size of the inorganic particles is too small, the inorganic particles may become difficult to handle due to aggregation, or uneven sintering may occur due to uneven mixing, so from this viewpoint, the particle size is preferably 0.1 μm or more.
The particle size referred to here means an average particle size, and is a particle size measured by a laser diffraction method.

Next, the prepared inorganic particles and phosphor particles are weighed.
The inorganic particles and the phosphor particles are weighed out so as to have a predetermined weight ratio with respect to the total weight of the inorganic particles and the phosphor particles. Here, the weight ratio of the inorganic particles to the total weight of the inorganic particles and the phosphor particles is appropriately set so as to obtain a desired wavelength conversion characteristic within a range of, for example, 20% or more and 95% or less, preferably 60% or more and 90% or less, more preferably 70% or more and 80% or less.
Furthermore, by appropriately selecting the particle size of the phosphor particles and the particle size of the inorganic particles within the above ranges, and by appropriately selecting the amount of the phosphor particles and the amount of the inorganic particles within the above ranges, the phosphor particles can be scattered among inorganic particles of relatively small particle size, and a sintered body 11 can be produced in which the phosphor particles are supported by an inorganic matrix formed by sintering the inorganic particles in the process described below.

(1-2) Mixing step S12
Next, the weighed inorganic particles and phosphor particles are mixed by, for example, placing them in a mixing vessel together with alumina balls and rotating them (ball mill mixing). The ball mill mixing may be performed using a wet mixing method that includes a solvent such as ethanol. Alternatively, a dry blend containing no solvent may be used.

(1-3) Molding process S13
Here, a powder mixture of inorganic particles and phosphor particles is molded into a predetermined shape.
The molding step S13 includes, for example, a primary molding step S131 and a secondary molding step S132.
In the primary molding step S131, pressure is applied from above and below by press molding or the like to perform primary molding. In the secondary molding step S132, the primary molded product is isotropically pressed by CIP (cold isostatic pressing) molding or the like to perform secondary molding. The material is molded into a desired shape so that the density after compression molding is uniform.

(1-4) Sintering step S14
In the sintering step, for example, if the inorganic particles are aluminum oxide, the inorganic particles are sintered by holding the inorganic particles at a predetermined sintering temperature of about 1300° C. or more and 1600° C. or less for a certain period of time to form a matrix-shaped support portion that supports the phosphor particles. The sintering step S14 includes, for example, a primary sintering step S141 in which sintering is performed at a predetermined temperature under atmospheric pressure, and a secondary sintering step S142 in which sintering can be performed at a higher density than the primary sintering step S141. In the primary sintering step S141, a spark plasma sintering (SPS) method can be used. In the secondary sintering step S142, a hot pressing (HP) method or a hot isostatic pressing (HIP) method can be used. The sintering temperature and time are appropriately set so as to sinter the inorganic particles while suppressing thermal deterioration and abnormal grain growth of the phosphor particles.

The sintering temperature and time are appropriately set in consideration of the particle size of the inorganic particles before sintering and the particle size of the phosphor particles before sintering so that the crystal particle size of the inorganic particles after sintering and the particle size of the phosphor particles after sintering are the desired size. When a YAG phosphor is selected as the phosphor particles and aluminum oxide is selected as the inorganic particles, and a hot press (HP) method is used, the sintering is performed at a temperature in the range of 1350° C. to 1600° C., for example, for a holding time at that temperature in the range of 30 minutes to 600 minutes.
The crystal grain size of the phosphor particles in the sintered body 11 can be measured, for example, by averaging the widths of the shortest and longest phosphor particles that are nearly circular in a SEM image of a scale that shows 10 phosphor particles in one cross section of the sintered body 11. In the following explanation and in the figures to be referred to, the phosphor particles in the sintered body 11 are indicated by the reference number 17.

(1-5) Processing process S15
The obtained sintered body 11 is processed into a predetermined shape as required. For example, as shown in FIG. 3A, the sintered body 11 is processed into a square prism shape of a predetermined dimension. The surface is substantially flat as shown in Fig. 3A. In this specification, "substantially flat" refers to the surface state of a normal sintered body after sintering, which has not been ground or polished. This means.

2. Recess formation step S2
In the recess forming step S2, the sintered body 11 prepared in the sintered body preparing step S1 is treated with acid to form a plurality of recesses 7 on the surface of the sintered body 11 as shown in FIG. 3B.
Here, a solution that dissolves at least one of the phosphor particles 17 and the inorganic particles is used. Preferably, a solution in which the dissolution rate of the phosphor particles 17 is greater than the dissolution rate of the inorganic particles is used. For example, phosphoric acid, sulfuric acid, hydrofluoric acid, and nitric acid can be mentioned.
The acid treatment is carried out, for example, by heating a mixture of phosphoric acid and sulfuric acid, and then immersing the material in the mixture for a predetermined period of time, followed by rinsing with water. The heating temperature is set, for example, in the range of 100° C. or higher and 320° C. or lower, and the treatment time is set, for example, in the range of 1 minute or higher and 60 minutes or lower, appropriately taking into consideration the shape and size of the desired recess 7, etc. By the above-mentioned acid treatment, the inorganic particles on the surface of the sintered body 11 and the spaces between the phosphor particles 17 are preferentially dissolved, and the sintered body 11 is regranulated. The gaps are preferentially dissolved and return to a particle state. Then, the phosphor particles 17 are released and the recesses 7 are formed on the surface of the sintered body 11.
For example, when the sintered body 11 containing the phosphor particles 17 made of YAG and inorganic particles made of aluminum oxide is subjected to an acid treatment using a mixture of phosphoric acid and sulfuric acid in a ratio of 36:74, the YAG is heated to 200° C. On the other hand, aluminum oxide starts to dissolve at about 260° C., so the temperature of the mixed liquid is set in the range of 280° C. to 305° C., for example. In this way, YAG dissolves faster than aluminum oxide. Since the ratio is high, the surface of the phosphor particle 17 is preferentially dissolved between the inorganic particle and the phosphor particle 17, and the inorganic particle and the phosphor particle 17 are separated, and the phosphor particle 17 is released. A recess 7 is formed on the surface of the sintered body 11 .

In this way, a plurality of recesses 7 are formed on the light reflecting surface 4 of the sintered body 11. In the sintered body 11 that has been subjected to the above-mentioned acid treatment, the distribution of the phosphor particles 17 on the light reflecting surface 4 is smaller than the distribution of the phosphor particles 17 inside the sintered body 11.
In the case of the sintered body 11 alone, the distribution of the phosphor particles 17 on the light reflecting surface 4 can be found as the ratio of the area of the phosphor particles 17 to the area of the light reflecting surface 4 by performing image analysis on an SEM image of the light reflecting surface 4. The distribution of the phosphor particles 17 inside the sintered body 11 can be found as the ratio of the area of the phosphor particles 17 to the area of the cross section of the sintered body 11 by performing image analysis on an SEM image of a cross section of the sintered body 11 including the central axis of the sintered body 11.
On the other hand, in the case of a wavelength conversion member 1 including a sintered body 11 and a reflecting member 21, when it is difficult to directly observe the light reflecting surface 4 in an SEM image, the distribution of the phosphor particles 17 on the light reflecting surface 4 can be obtained by, for example, image analysis of an SEM image of a cross section of the sintered body 11 crossing the light reflecting surface 4 as shown in FIG. 3H, as a ratio of the length of the portion where the phosphor particles 17 overlap on the line L4 of the light reflecting surface 4 to the length of the line L4 of the light reflecting surface 4. The distribution of the phosphor particles 17 inside the sintered body 11 can be obtained by image analysis of an SEM image of a cross section of the sintered body 11 including the central axis of the sintered body 11, by drawing a virtual line L40 corresponding to the line L4 tracing the light reflecting surface 4, as a ratio of the length of the portion where the phosphor particles 17 overlap on the virtual line L40 to the length of the virtual line L40. Here, FIG. 3H shows an enlarged view of a portion of the range to be image-analyzed, and it goes without saying that the range to be image-analyzed in the SEM image when actually obtaining the distribution is set to a certain range or more, for example, a scale in which 100 phosphor particles 17 are reflected, so that the distribution does not differ depending on the analysis position. The distribution of the phosphor particles 17 on the light-reflecting surface 4 is, for example, 0.3 times or less, preferably 0.1 times or less, and more preferably, approximately 0, of the distribution of the phosphor particles 17 inside the sintered body 11. By making such a phosphor particle distribution, more inorganic particles are distributed on the light-reflecting surface 4 of the sintered body 11, so that the confinement of light on the light-reflecting surface 4 of the sintered body 11 can be improved. This is considered to be due to the difference in refractive index between the inorganic particles and the voids 9 of the recesses 7. It is also considered to be due to the reduction in the phosphor particles 17 exposed on the light-reflecting surface 4 of the sintered body 11. Note that FIG. 3H is a simplified schematic diagram for explaining a method for evaluating the distribution of the phosphor particles 17, and although it is a cross-sectional view, hatching is omitted to make it easier to understand the line L4 and the virtual line L40. In addition, in FIG. 3H, the phosphor particles 17 are drawn as circles having the same diameter, but in reality, the particle size and shape of each phosphor particle 17 are different.

In other words, in the sintered body 11, the distribution of the phosphor particles 17 in the peripheral region 111 including the light reflecting surface 4 is smaller than the distribution of the phosphor particles 17 in the internal region 112 inside the peripheral region 111. Here, the peripheral region 111 including the light reflecting surface 4 of the sintered body 11 refers to a region at a certain distance inward from the light reflecting surface 4 of the sintered body 11. The certain distance depends on the conditions such as the temperature and time of the acid treatment, but is, for example, 5 μm or more and 20 μm or less. The density of the phosphor particles 17 in the peripheral region 111 including the light reflecting surface 4 of the sintered body 11 is, for example, 0.3 times or less, preferably 0.1 times or less, and more preferably, the density is almost 0, of the density of the phosphor particles 17 in the internal region 112. By making such a phosphor particle distribution, more inorganic particles are distributed in the peripheral region 111 including the light reflecting surface 4 of the sintered body 11, so that the confinement of light in the light reflecting surface 4 of the sintered body 11 can be improved. This is believed to be due to the difference in refractive index between the inorganic particles and the voids 9 in the recesses 7. It is also believed to be due to a decrease in the phosphor particles 17 exposed to the light reflecting surface 4 of the sintered body 11. This also reduces color unevenness in the peripheral region 111 and the internal region 112 of the sintered body 11 when the sintered body 11 is irradiated with light.

Furthermore, the acid treatment causes the phosphor particles 17 to separate from the sintered body 11, thereby forming voids 9 surrounded by the sintered body 11 in the peripheral region 111 including the light reflecting surface 4 of the sintered body 11. This further enhances the confinement of light at the light reflecting surface 4 of the sintered body 11. Here, being surrounded by the sintered body 11 means that the sintered body 11 is present in 40% or more and 80% or less of the periphery of the voids 9 in one cross section of the sintered body 11.
The porosity of the peripheral region 111 including the light reflecting surface 4 of the sintered body 11 is preferably 5% or more and 30% or less. This makes it possible to improve the confinement of light at the light reflecting surface 4 while maintaining the strength of the sintered body 11.

3. Reflective member arrangement step S3
Here, a reflecting member 21 is disposed in contact with and surrounding the outer peripheral side surface of a columnar sintered body 11 having a recess 7 formed on its surface. The outer peripheral side surface of the sintered body 11 is a light reflecting surface 4.
For example, the powder for the reflecting member forming the reflecting member 21 is molded and sintered integrally so as to surround the columnar sintered body 11 arranged at a predetermined position. The powder for the reflecting member forming the reflecting member 21 is molded, for example, by a slip cast method, a doctor blade method, or the like so as to surround the sintered body 11 arranged at a predetermined position. Pressure may be applied during or after this molding to pack more densely. This produces a wavelength conversion member 1 in which the columnar sintered body 11 and the reflecting member 21 are integrated. Note that when the powder for the reflecting member forming the reflecting member 21 is sintered, the sintered body 11 is sintered in advance, so that the shape of the columnar sintered body 11 including the recesses 7 formed on the surface is maintained without substantial deformation even after integration with the reflecting member 21. After the reflecting member 21 is arranged, the surface other than the light reflecting surface 4 of the sintered body 11 covered with the reflecting member 21, in other words, a part or all of the surface exposed from the reflecting member, can be ground or polished as necessary to remove the recesses 7 formed on the surface.

The reflecting member 21 is preferably made of the same material as the inorganic particles of the sintered body 11, and for example, a material containing aluminum oxide as a main raw material and also containing a material with a refractive index different from that of aluminum oxide can be used.
Here, for example, when the powder for the reflecting member is molded by the slip casting method, the doctor blade method, or the like, the powder for the reflecting member may penetrate into a part or all of the recessed portion 7 of the sintered body 11. In this case, at the boundary between the light reflecting surface 4 of the sintered body 11 and the reflecting member 21a, an intermediate region is formed, which includes the recessed portion 7 of the sintered body 11, at least a part of the protruding portion 8 of the reflecting member 21a extending into the recessed portion 7, and the gap 9 formed between the recessed portion 7 and the protruding portion 8. Here, the intermediate region refers to, for example, a region at a certain distance from the boundary between the light reflecting surface 4 of the sintered body 11 and the reflecting member 21a on the sintered body 11 side and the reflecting member 21a side, depending on the conditions such as the temperature and time of the acid treatment. The certain distance refers to, for example, a region of 3 μm or more and 10 μm or less, depending on the conditions such as the temperature and time of the acid treatment.
It should be noted that the recess 7 of the sintered body 11, the protrusion 8 of the reflecting member 21a, and the gap 9 formed between the recess 7 and the protrusion 8 are not shown in the schematic diagram, but are shown in Figures 7A and 7B.

Here, in the reflecting member arrangement step S3, as shown in Figures 3C to 3F, a wavelength conversion member assembly in which multiple wavelength conversion members 1 are produced at once may be produced. After that, a singulation step may be included in which the wavelength conversion member assembly is divided to produce multiple wavelength conversion members 1. Each wavelength conversion member 1 after the division includes one or more sintered bodies 11a. Specifically, by processing the wavelength conversion member assembly shown in Figure 3C to a predetermined thickness, multiple wavelength conversion member assemblies including multiple wavelength conversion members 1 shown in Figures 3D and 3E may be formed, and the wavelength conversion member assembly may be further divided into individual wavelength conversion members 1 to obtain the wavelength conversion member 1 shown in Figure 3F. In this way, when the wavelength conversion member assembly is processed to a predetermined thickness and further singulated, the surface of the sintered body 11a exposed on the processed surface of the wavelength conversion member 1 has the recess 7 removed, suppressing light confinement, and can be used, for example, as the light incident surface 5 or the light exit surface 6 without undergoing a separate step of removing the recess 7. In addition, since the wavelength conversion member assembly is processed to a predetermined thickness, when the wavelength conversion member 1 includes two or more sintered bodies 11a, the light entrance surface and/or light exit surface of the two or more sintered bodies 11a are located on approximately the same plane.

The wavelength conversion member 1 produced as described above includes a sintered body 11a and a reflecting member 21a, the side of the sintered body 11a is covered by the reflecting member 21a, and the upper and lower surfaces of the sintered body 11a are exposed from the reflecting member 21a. In other words, a part of the inner peripheral side surface of the reflecting member 21a contacts the outer peripheral side surface of the sintered body 11a, and the light incident surface and light exit surface of the sintered body 11a are exposed from the reflecting member 21a. As a result, for example, as shown in FIG. 3G, the lower surface of the sintered body 11a can be used as the light incident surface 5 to allow light from a light emitting element 80 such as a laser diode to enter, and the upper surface can be used as the light exit surface 6 to allow light after wavelength conversion to exit. In this way, when the lower surface of the sintered body 11a is used as the light incident surface 5 and the upper surface is used as the light exit surface 6, in order to suppress light confinement in the light incident surface 5 and the light exit surface 6, it is preferable to include a recess removal step of removing the recess 7 of the light incident surface 5 and/or the light exit surface 6 after the recess formation step S2. In the first embodiment, the process of forming the wavelength conversion member 1 by the above-mentioned processing also serves as the recess removal process.

In addition, in the wavelength conversion member 1 configured as described above, the light reflecting surface 4 of the sintered body 11a has a plurality of recesses 7, and the surface of the reflecting member 21a facing the light reflecting surface 4 of the sintered body 11a has a plurality of protrusions 8. At least a portion of the protrusions 8 of the reflecting member 21a enters into the recesses 7 formed on the light reflecting surface 4 of the sintered body 11a, and at least a portion of the recesses 7 also has voids 9. That is, an intermediate region in which a plurality of recesses 7, a plurality of protrusions 8, and voids 9 exist is formed at the boundary between the light reflecting surface 4 of the sintered body 11a and the surface of the reflecting member 21a facing it. By forming this intermediate region, the inorganic particles or voids 9 forming the recesses 7 of the sintered body 11a and the interface between the protrusions 8 of the reflecting member 21a suppress the propagation of light from the sintered body 11a, thereby increasing the luminance difference between the light exit surface 6 of the sintered body 11a and the outside of the light exit surface 6 when observed from above. Furthermore, if the lower surface of the sintered body 11a is the light incident surface 5 and the upper surface is the light exit surface 6, an optical thin film such as a DBR (Distributed Bragg Reflector) film may be formed on the light incident surface 5 of the sintered body 11a.

In the wavelength conversion member 1 produced through the above process, the light reflecting surface 4 of the sintered body 11a covered with the reflecting member 21a has multiple recesses 7 formed by acid treatment, improving light confinement. As a result, when the upper surface of the sintered body 11a surrounded by the reflecting member 21a is used as the light emitting surface 6, the luminance difference between the light emitting surface 6 and the reflecting member 21a in the vicinity of the light emitting surface 6 is large; in other words, the rate of decrease in luminance with respect to the distance from the light emitting surface 6 on the upper surface of the wavelength conversion member 1 (the surface including the light emitting surface 6 of the sintered body 11a) can be made steep, resulting in good visibility.

The wavelength conversion member 1 produced in the above manner can be used, for example, as a lid or part of a lid for a package that houses a light-emitting diode or a semiconductor laser element, and can convert the wavelength of light from the light-emitting diode or semiconductor laser element housed in the package and emit it.

Embodiment 2.
The method for producing the wavelength conversion member 2 of embodiment 2 is similar to the method for producing the wavelength conversion member 1 of embodiment 1, and includes a sintered body preparation step S1, a recess formation step S2, and a reflective member arrangement step S3, but the specific content of each step is partially different from embodiment 1.
A method for producing the wavelength conversion member 2 of the second embodiment will be described in detail below.

1. Sintered body preparation step S1
The sintered body preparation step S1 includes, as in the first embodiment, (1-1) a weighing step S11, (1-2) a mixing step S12, (1-3) a molding step S13, (1-4) a sintering step S14, and (1-5) a processing step S15, as shown in FIG.
In the second embodiment, the (1-1) weighing step S11 and the (1-2) mixing step S12 are the same as those in the first embodiment.
In the second embodiment, the weighed and mixed inorganic particles and phosphor particles are used to form a plate-shaped molded body having a predetermined thickness in the (1-3) molding step S13.
In the second embodiment, for example, in the molding step S13, a binder made of resin and a solvent are added to the mixed powder of inorganic particles and phosphor particles, and the mixture is stirred to prepare a slurry. The slurry is then formed into a film of a predetermined thickness, and then cut into a predetermined shape to prepare a plate-shaped green compact. In the molding step of the second embodiment, the green compact may be molded into a plate shape by press molding and/or CIP (cold isostatic pressing) molding, etc., in the same manner as in the first embodiment.
The thickness of the plate-like molded body is set so that the thickness after sintering will be a desired thickness, taking into consideration the shrinkage due to sintering described below.

Next, in the sintering step (1-4) S14, the plate-shaped molded body is sintered in the same manner as in embodiment 1 to produce a sintered body, the phosphor ceramic plate 12.

(1-5) Processing process S15
As shown in Fig. 4A, a plurality of convex portions 12a having a truncated cone shape are formed on the upper surface of the obtained phosphor ceramic plate 12. The convex portions 12a can be formed, for example, by a machining center or the like. The portion of the phosphor ceramic plate 12 excluding the plurality of protrusions 12 a is referred to as a base portion 12 b.

2. Recess formation step S2
In embodiment 2, the recess forming step S2 includes:
(i) an acid treatment step in which the entire phosphor ceramic plate 12 is subjected to an acid treatment to form recesses 7 on the entire surface of the phosphor ceramic plate 12;
(ii) a second processing step of removing the recesses 7 on the predetermined surface and then separating the sintered body 12a into a predetermined shape;
Includes.

In the acid treatment step S2 of the recess formation step of the second embodiment, the entire phosphor ceramic plate 12 on which the plurality of protrusions 12a are formed is subjected to an acid treatment to form a plurality of recesses 7 on the entire surface of the phosphor ceramic plate 12 including the surfaces of the plurality of protrusions 12a, as shown in Fig. 4B. The acid treatment is performed in the same manner as in the first embodiment.

(2-2) Second Processing Step In the second processing step, first, the upper surfaces of the multiple truncated cone-shaped protrusions 12a are ground to remove the recesses 7 formed on the upper surfaces, and the upper surfaces are made flat as shown in FIG. 4C.
Next, the base portion 12b is removed by grinding from the lower surface of the phosphor ceramic plate 12, and the plurality of truncated cone-shaped protrusions 12a are separated into individual pieces as shown in FIG. 4D.
In this manner, a sintered body 12a having a truncated cone shape is produced, the upper and lower bottom surfaces of which are flat, and the recesses 7 formed on the outer peripheral side surface by acid treatment.
In this specification, the upper base or upper base surface of the truncated cone shape refers to the smaller area of the circular surfaces facing each other across the side surface, regardless of the vertical positional relationship, and the larger area of the opposing circular surfaces is referred to as the lower base or lower base surface.

3. Reflective member arrangement step S3
Here, a reflecting member 22 is disposed in contact with and surrounding the outer peripheral side surface of a columnar sintered body 12a having a recess 7 formed on its surface. The outer peripheral side surface of the sintered body 12a is the light reflecting surface 4.
Specifically, first, the reflecting member 22 is separately prepared, in which a through hole is formed and the sintered body 12a having a truncated cone shape is inserted therein. For example, the powder for the reflecting member forming the reflecting member 22 is molded to prepare a molded body having a through hole, and the molded body is sintered to prepare the reflecting member 22. After sintering, the through hole may be ground or polished to a predetermined dimensional accuracy. In this way, the sintered body 12a having a truncated cone shape can be placed in the through hole with high positional accuracy. The through hole of the reflecting member 22 has the same truncated cone shape as the sintered body 12a, and is formed so that the opening surface of the upper base is smaller than the upper base of the sintered body 12a and the opening surface of the lower base is larger than the lower base of the sintered body 12a. In the second embodiment, ceramic is used as the reflecting member 22, but for example, metal can also be used.
Here, before placing the sintered body 12a in the through hole of the reflecting member 22, low melting point glass can be formed on the inner wall of the through hole. Then, the sintered body 12a can be fused into the through hole of the reflecting member 22 using the low melting point glass, thereby fixing the sintered body 12a in the through hole of the reflecting member 22. This makes it possible to improve the heat dissipation from the sintered body 12a and the fixing strength even if the inclination angle of the through hole of the reflecting member 22 and the inclination angle of the side surface of the sintered body 12a are not the same. Note that the inclination angle of the through hole of the reflecting member 22 and the inclination angle of the side surface of the sintered body 12a may be the same.

Next, as shown in Fig. 4F, the truncated cone-shaped sintered body 12a is inserted into the through-hole of the reflecting member 22. As described above, the through-hole is formed so that the opening surface of the upper base is smaller than the upper base of the sintered body 12a and the opening surface of the lower base is larger than the lower base of the sintered body 12a, so that the sintered body 12a is held in the middle of the through-hole, i.e., so that cavities are formed on both the upper and lower sides of the through-hole, as shown in Fig. 4F.
4G, the through hole into which the sintered body 12a has been inserted is placed with the bottom side of the cavity facing up, and glass 18 is applied and melted in the cavity, and the glass 18 is placed on the sintered body 12a. In the second embodiment, the glass 18 contains a phosphor, but it may be configured not to contain a phosphor, or may contain a light diffusing material or the like.
Thereafter, the glass 18 protruding from the through hole is ground and/or polished so that the surface of the glass 18 and the upper surface of the reflecting member 22 form the same plane as shown in FIG. 4H.

The wavelength conversion member 2 of the second embodiment produced as described above includes a sintered body 12a and a reflecting member 22, and the side of the frustum-shaped sintered body 12a is covered by the reflecting member 22, and the upper and lower surfaces of the sintered body 12a are exposed from the reflecting member 22. As a result, for example, as shown in FIG. 4I, the lower surface of the sintered body 12a can be used as the light incident surface 5 to allow light from a light emitting element 80 such as a laser diode to enter, and the upper surface can be used as the light exit surface 6 to allow light after wavelength conversion to exit. In this way, when the lower surface of the sintered body 12a is used as the light incident surface 5 and the upper surface is used as the light exit surface 6, in order to suppress light confinement in the light incident surface 5 and the light exit surface 6, it is preferable to include a recess removal step of removing the recess 7 of the light incident surface 5 and/or the light exit surface 6 after the recess formation step S2. In the second embodiment, the process of grinding and/or polishing the upper surface of the convex portion 12a and the process of removing the base portion 12b to separate the multiple convex portions 12a in the second processing process described above also serve as a recess removing process. In addition, when the lower surface of the sintered body 12a is the light incident surface 5 and the upper surface is the light exit surface 6, an anti-reflection film may be formed on the light incident surface 5 of the sintered body 12a.

In the wavelength conversion member 2 produced through the above process, the light reflecting surface 4 of the sintered body 12a covered with the reflecting member 22 has multiple recesses 7 formed by acid treatment, improving light confinement. As a result, when the upper surface of the sintered body 12a surrounded by the reflecting member 22 is used as the light emitting surface 6, the luminance difference between the light emitting surface 6 and the reflecting member 22 in the vicinity of the light emitting surface 6 is large; in other words, the rate of decrease in luminance with respect to the distance from the light emitting surface 6 on the upper surface of the wavelength conversion member 2 (the light emitting surface 6 of the sintered body 12a and the upper surface of the reflecting member 22 surrounding it) can be made steep, resulting in good visibility.

The wavelength conversion member 2 produced in the above manner can be used, for example, as a lid or part of a lid for a package that houses a light-emitting diode or semiconductor laser element, and can convert the wavelength of light from the light-emitting diode or semiconductor laser element housed in the package and emit it.

Embodiment 3
The method of manufacturing the wavelength conversion member 3 of embodiment 3, like the methods of manufacturing the wavelength conversion members of embodiments 1 and 2, includes a sintered body preparation step S1 and a recess formation step S2 as shown in FIG. 5 . However, it differs from embodiment 2 in that in the recess formation step S2, the shape processing of the sintered body 13 and the formation of the recesses 7 on the surface are carried out in a single step.
Moreover, the wavelength conversion member 3 produced by the manufacturing method of the third embodiment converts the wavelength of light incident from the upper surface and then emits the light from the upper surface, i.e., the light incident surface 5 and the light exit surface 6 are the same surface. Therefore, the manufacturing method of the third embodiment includes a reflective film forming step of forming a reflective film 23 on the lower surface of the sintered body 13, instead of the reflective member arrangement step S3 of the first and second embodiments, as shown in FIG.
A method for producing the wavelength conversion member 3 of the third embodiment will be described in detail below.

1. Sintered body preparation step S1
In the manufacturing method of the wavelength conversion member 3 of embodiment 3, in the sintered body preparation step S1, a plate-shaped body is prepared in the same manner as in embodiment 2, and the plate-shaped body is sintered to produce a sintered body, namely, a phosphor ceramic plate 13.

2. Recess formation step S2
In the manufacturing method of the third embodiment, the recess forming step S2 is a step of shaping the upper surface of the phosphor ceramic plate 13 and forming the recesses 7 on the shaped surface.
Specifically, first, as shown in FIG. 6A, a plurality of masks 53 made of, for example, SiO ₂ and having a rectangular planar shape when viewed from above are formed at predetermined intervals on the upper surface of the phosphor ceramic plate 13. At this time, a protective film 55 made of, for example, a _SiO2 film can be formed on the entire lower surface of the phosphor ceramic plate 13 that is not subjected to shaping. Alternatively, etching may be performed without forming the film 55, and the lower surface on which the recesses 7 are formed may be ground or polished in a later step. Since grinding or polishing the lower surface of the phosphor ceramic plate 13 may cause the phosphor ceramic plate 13 to crack, in such a case, it is preferable to form a protective film 55 . Here, the mask 53 formed on the upper surface of the phosphor ceramic plate 13 and the protective film 55 formed on the lower surface _thereof are not limited to _SiO2 , but may be, for example, SiON, SiN, _Al2O3 , AlON, AlN, _ZrO2 can be used, but any material that is not etched by the acid treatment described below will suffice.

Next, the phosphor ceramic plate 13 having the mask 53 formed on the upper surface and the protective film 55 formed on the lower surface is subjected to an acid treatment. The acid treatment is performed in the same manner as in the first embodiment, for example, by heating a mixture of phosphoric acid and sulfuric acid, and performing the acid treatment for a predetermined time in the mixture, and then washing with water. As described in the first embodiment, this acid treatment preferentially dissolves the inorganic particles near the surface of the sintered body 13 (phosphor ceramic plate 13) and the phosphor particles 17 between the particles, and the phosphor particles are released, but inorganic particles made of, for example, aluminum oxide are also dissolved by the mixture of phosphoric acid and sulfuric acid at a certain temperature or higher. Therefore, the phosphor ceramic between the masks 53 on the upper surface is removed by etching, and as shown in FIG. 6C, convex portions 13a are formed at the lower portions of the masks 53, and a plurality of concave portions 7 are formed on the surface formed by the etching. For example, when a mask 53 having a rectangular planar shape is formed and acid treatment is performed, the etching by the acid treatment is isotropic, so that the convex portions 13a formed on the lower part of the mask 53 are each approximately quadrangular pyramid shaped, and a plurality of concave portions 7 are formed on the side surfaces of the approximately quadrangular pyramid shaped convex portions 13a. Here, in the region of the upper surface of the phosphor ceramic plate 13 where the mask 53 is not formed, for example, half-cutting is performed by dicing or laser, etc., and then etching is performed, so that the acid can be more easily penetrated. This allows etching to be performed deeper than when the half-cutting is not performed. As a result, the propagation of light in the phosphor ceramic plate 13 can be further suppressed, and the parting can be improved.
The upper surface of the approximately quadrangular pyramid-shaped protrusion 13 a , that is, the surface in contact with the mask 53 , and the upper surface of the mask 53 are both substantially flat, which is suitable for the light incident and exit surfaces of the phosphor ceramic plate 13 .

In the acid treatment of embodiment 3, the ratio of phosphoric acid to sulfuric acid, the heating temperature of the mixed solution, the treatment time, etc. are set so that the desired recesses 7 are formed in the same manner as in embodiment 1, etc., but since the acid treatment of embodiment 3 also serves to shape the upper surface of the phosphor ceramic plate 13, the ratio of phosphoric acid to sulfuric acid, the heating temperature of the mixed solution, the treatment time, etc. may be adjusted taking into further consideration the shape of the protrusions 13a to be formed.

3. Reflective Film Forming Process After the acid treatment, as shown in FIG. 6D, a reflective film 23 is formed on the entire lower surface of the phosphor ceramic plate 13. The reflective film 23 may be directly in contact with the lower surface of the phosphor ceramic plate 13, i.e., the protective film 55 may be removed and formed directly on the lower surface of the phosphor ceramic plate 13, or, for example, when the protective film 55 is a SiO ₂ film and has light-transmitting properties, the reflective film 23 may be formed on the lower surface of the phosphor ceramic plate 13 via the protective film 55. In FIG. 6D, the protective film 55 is assumed to have light-transmitting properties, and the reflective film 23 is formed on the lower surface of the phosphor ceramic plate 13 via the protective film 55. As the reflective film 23, a dielectric multilayer film such as a DBR (Distributed Bragg Reflector) film and/or a metal film can be used. When the uppermost film among the films constituting the reflective film 23 is a dielectric film constituting a part of the DBR film, it is preferable to provide a film having a refractive index between the refractive index of the uppermost dielectric film and the refractive index of the phosphor particles 17 in the phosphor ceramic plate 13 as the protective film 55. In addition, when the protective film 55 for protecting the phosphor ceramic plate 13 from the acid treatment is made of a material that does not satisfy these refractive index conditions, such as a SiO ₂ film, the protective film 55 may be removed once and then re-formed to satisfy these conditions. As a result, when the phosphor particles 17 form a part of the lower surface of the phosphor ceramic plate 13, the light from the phosphor particles 17 can be totally reflected at the interface between the protective film 55 and the top dielectric film. As a result, the amount of light that is directly incident at a relatively high angle from the phosphor particles 17 can be reduced, so that the number of layers of the DBR film can be reduced compared to when such a protective film 55 is not provided. The thickness of the protective film 55 and the top dielectric film of the DBR film can be made larger than the wavelength of the light to be reflected, for example, 800 nm or more. The thickness of the protective film 55 may be made larger than the thickness of the top dielectric film of the DBR film. Examples of materials for the dielectric film that constitutes the DBR include Nb ₂ O ₅ , Ta ₂ O ₅ , ZrO ₂ , and SiO ₂ . For example, when the top dielectric film of the DBR film is a _SiO2 film and the phosphor particles 17 are YAG phosphors, the material of the protective film 55 having a refractive index between those refractive indices can be _Al2O3 , _{MgO ,} or _Ga2O5 . Since these materials of the protective film 55 have a higher thermal conductivity than the above-mentioned materials of the DBR film, by forming the protective film 55 with any of these materials, it is expected that the effect of improving heat dissipation can be achieved. In addition, when total reflection is caused at the interface between the protective film 55 and the top dielectric film, the thickness of the protective film 55 may be made thicker than the optimal thickness calculated by optical simulation. It is considered that this can reduce the probability that total reflection does not occur at the interface between those films.

4. Support Joining Step In this step, a support 33 that supports the phosphor ceramic plate 13 from the lower surface side is joined, for example, onto the reflective film 23. The support 33 is made of, for example, aluminum nitride or copper. This support 33 supports or protects the phosphor ceramic plate 13 and is joined as necessary, and the support joining step is optional.

When light that excites the phosphor particles 17 is incident on the upper surfaces of the convex portions 13a of the wavelength conversion member 3 of embodiment 3 produced as described above through the light-transmitting mask 53, at least a part of the incident light excites the phosphor, and the excited phosphor emits light of a wavelength different from that of the incident light, which is emitted to the outside through the upper surfaces of the convex portions 13a and the mask 53. The mask 53 may be removed after the recess formation step S2.
In this manner, the wavelength conversion member 3 of the third embodiment converts the wavelength of at least a portion of the incident light incident from the upper surface of the convex portion 13a through the mask 53, and then emits the light to the outside through the upper surface of the convex portion 13a and the mask 53. At this time, since a plurality of concave portions 7 are formed on each of the outer peripheral side surfaces of the convex portion 13a, the emission of light from the side surface of the convex portion 13a is suppressed, and the light can be confined inside the convex portion 13a, so that the luminance difference of the emitted light between the light emission surface 6 and the outside thereof can be increased, and the wavelength can be efficiently converted.
In addition, in the wavelength conversion member 3 of embodiment 3, at least a portion of the incident light may be wavelength converted and emitted, and the remaining portion may be reflected and/or scattered within the phosphor ceramic 13 to be emitted at the same wavelength as when it was incident. In this case, a mixture of light with the same wavelength as the incident light and light with a different wavelength from the incident light after wavelength conversion is emitted.

The wavelength conversion member 3 of the third embodiment manufactured as described above can be used in projectors, lighting, and vehicle lamps by combining it with an excitation light source such as a light-emitting diode or a semiconductor laser element. In addition, for example, by providing the support 33 with a heat dissipation function, it can be used as the wavelength conversion member 3 for a light source with a large amount of light.

Figure 6F shows a schematic diagram of a light-emitting device of an application example including the wavelength conversion member 3 of embodiment 3, and the light-emitting device includes the wavelength conversion member 3 and a light-emitting element 80 that is a laser diode that irradiates the convex portion 13a of the wavelength conversion member 3 with laser light. In the light-emitting device shown in Figure 6F, the laser light emitted from the light-emitting element 80 is incident on the upper surface of the convex portion 13a, and at least a part of the incident light is converted by the phosphor into light of a wavelength different from the incident light and emitted from the upper surface of the convex portion 13a. The outer peripheral side surface of the convex portion 13a is a light-reflecting surface 4 with improved light confinement, so that the amount of light leaking from the outer peripheral side surface of the convex portion 13a can be reduced, and the laser light incident on the upper surface of the convex portion 13a can be efficiently wavelength-converted and emitted from the upper surface of the convex portion 13a.

In FIG. 6F, one light-emitting element 80 is shown irradiating laser light onto one convex portion 13a, but for example, multiple light-emitting elements 80 may be provided and each light-emitting element 80 may irradiate its corresponding convex portion 13a (configuration 1), or one light-emitting element 80 may be used to irradiate multiple convex portions 13a (configuration 2).

Specifically, in configuration 1, the number of light-emitting elements 80 and the number of convex portions 13a may differ depending on the application, and laser light may be irradiated from one light-emitting element 80 to two or more convex portions 13a, or laser light may be irradiated from two or more light-emitting elements 80 to one convex portion 13a.
In addition, in configuration 2, depending on the application, the laser light of one light-emitting element 80 may be, for example, optically expanded and irradiated simultaneously onto a plurality of convex portions 13a, or the laser light may be scanned and shifted in time by using, for example, a mirror capable of controlling the direction, so that the laser light is irradiated sequentially onto different convex portions 13a.

Experimental Example

As an experimental example, a sintered body containing Al ₂ O ₃ particles as inorganic particles and YAG (Yttrium Aluminum Garnet) phosphor particles as phosphor particles was prepared, and the upper surface of the sintered body was treated with acid. Then, the light transmittance of the upper surface of the sintered body was evaluated when light was incident from the lower surface of the sintered body.

Specifically, aluminum oxide particles having an average particle size of 0.5 μm were prepared as inorganic particles, and YAG phosphor particles having an average particle size of 5 μm were prepared as phosphor particles, and the aluminum oxide particles and the YAG phosphor particles were mixed in a ratio of 8:2.
The mixing was carried out by wet mixing for 24 hours.

The mixed powder was then formed into a cylinder shape.
The green sheet was primarily molded using a doctor blade method, and the primarily molded product was then secondarily molded into a columnar shape using a cutter.

The moulded part was then sintered.
The sintering was carried out by primary sintering in the atmosphere at a temperature of 1400° C. for 5 hours by atmospheric sintering, and then annealing (heat treatment) was carried out in an inert gas atmosphere at a temperature of 1400° C. for 10 hours.

After sintering, the sintered body was subjected to an acid treatment to form a plurality of recesses on the upper surface of the sintered body.
For the acid treatment, a mixed liquid of phosphoric acid and sulfuric acid in a ratio of 1:3 was heated to 180°C and the sintered body was placed in it. Thereafter, the sintered body was placed in another mixed liquid of the same type but at a temperature of 300°C. After 10 minutes had elapsed, the sintered body was placed in the mixed liquid at 180°C, and the temperature was gradually lowered before being removed.

After the acid-treated sintered body was washed with water, light was made to enter the bottom surface of the sintered body, and the light transmittance at the top surface of the sintered body was measured.
The light transmittance was measured by a spectrophotometer.

In addition, the sintered body of the comparative example was prepared in the same manner as the example up to the annealing step, and the light transmittance was measured in the same manner as the experimental example, without undergoing acid treatment.

As a result, the light transmittance of the top surface of the sintered body of the experimental example was 55% at 540 nm, whereas the light transmittance of the top surface of the sintered body of the comparative example was 60% at 540 nm. In other words, the light transmittance of the top surface of the sintered body of the experimental example was lower than the light transmittance of the top surface of the sintered body of the comparative example, and it was found that the light confinement was improved in the top surface of the sintered body of the experimental example compared to the comparative example.

Figure 7A shows a cross-sectional photograph of the reflective member 21a formed on the light-reflecting surface 4 of the sintered body 11a produced in the same manner as in the experimental example. As shown in Figure 7A, it was confirmed that the distribution of phosphor particles 17 on the light-reflecting surface 4 was less than the distribution of phosphor particles 17 inside the sintered body 11a. It was also confirmed that the reflective member 21a penetrated into the recessed portion 7 of the sintered body 11a, and the protruding portion 8 of the reflective member 21a was formed. Figure 7B shows a cross-sectional photograph of the reflective member 21a removed from Figure 7A so that the shape of the light-reflecting surface 4 can be easily understood. As shown in Figure 7B, it was confirmed that a gap 9 remains between the recessed portion 7 of the sintered body 11a and the protruding portion 8 of the reflective member 21a. Here, the reflective member 21a was formed by using a slip casting method, pouring a slurry to become the reflective member 21a around the sintered body 11a, drying it, and then heat-treating it at 1400 ° C. in an air atmosphere for 1 hour.

In contrast, when a reflective member was formed on the light-reflecting surface of the sintered body of the comparative example that had not been subjected to acid treatment, as shown in Figure 7C, no difference was observed between the distribution of phosphor particles on the light-reflecting surface and the distribution of phosphor particles inside the sintered body. Furthermore, no recesses where the reflective member had entered were observed, as was the case in the experimental example.

REFERENCE SIGNS LIST 1, 2, 3 Wavelength conversion member 4 Light reflecting surface 5 Light incident surface 6 Light emitting surface 7 Concave portion 8 Convex portion 9 Void 11, 11a Sintered body 12 Sintered body (phosphor ceramic plate)
12a Sintered body (protruding portion)
12b Base portion 13 Sintered body (phosphor ceramic plate)
13a: convex portion 17: phosphor particle 18: glass 21, 21a, 22: reflective member 23: reflective film 33: support 53: mask 55: protective film 80: light emitting element L4: line L40: imaginary line

Claims (10)

A method for producing a wavelength conversion member including a sintered body having a light incident surface, a light exit surface, and a light reflecting surface that is different from the light incident surface and the light exit surface, comprising:
a sintered body preparation step of preparing a sintered body containing inorganic particles and phosphor particles;
a recess forming step of treating the sintered body with acid to form a plurality of recesses on a light reflecting surface of the sintered body;
a reflecting member disposing step of disposing a reflecting member on the outer peripheral side surface of the sintered body, the outer peripheral side surface being the light reflecting surface, the reflecting member being in contact with the outer peripheral side surface and exposing the light incident surface and the light exit surface;
The reflective member arrangement step includes:
forming a powder for a reflecting member integrally with the sintered body having the plurality of recesses formed therein;
sintering the powder for reflection member and the sintered body having the plurality of recesses integrally;
A method for producing a wavelength conversion member, comprising : In the recess forming step, a plurality of recesses are formed on a light incident surface and/or a light emitting surface of the sintered body,
After the recess forming step,
The method for producing a wavelength conversion member according to claim 1 , further comprising a recess removing step of removing recesses on the light incident surface and/or the light exit surface. The sintered body has a columnar shape .
A method for producing the wavelength conversion member according to claim 1 or 2. In the sintered body preparation step, two or more sintered bodies are prepared,
The reflective member arrangement step includes:
forming the powder for the reflecting member integrally so as to surround each of the sintered bodies having the plurality of recesses;
The powder for the reflection member and the sintered body having the plurality of recesses formed therein are integrally sintered to produce a wavelength conversion member assembly,
The method for producing a wavelength conversion member according to any one of claims 1 to 3, further comprising a singulation step of dividing the wavelength conversion member assembly into a plurality of wavelength conversion members each including the one or more sintered bodies. The method for manufacturing a wavelength conversion member according to claim 1, wherein in the recess forming step, a mask is formed on the light incident surface and/or the light exit surface of the sintered body, and multiple recesses are formed on the surface exposed from the mask. The method for producing a wavelength conversion member according to any one of claims 1 to 5 , wherein the light incident surface and the light exit surface are formed by the same surface. a sintered body having a light incident surface, a light exit surface, and a light reflecting surface which is different from the light incident surface and the light exit surface, the sintered body including phosphor particles; and a reflecting member provided in contact with the outer peripheral side surface so as to expose the light incident surface and the light exit surface, the sintered body and the reflecting member being sintered integrally ,
The light reflecting surface of the sintered body has a plurality of recesses,
A wavelength conversion member, characterized in that the distribution of phosphor particles on the light reflecting surface is smaller than the distribution of phosphor particles inside the sintered body. The wavelength conversion member according to claim 7 , further comprising a void surrounded by the sintered body in a peripheral region of the sintered body. The wavelength conversion member according to claim 7 or 8 , wherein a part of an inner peripheral side surface of the reflecting member is in contact with the outer peripheral side surface. The wavelength conversion member according to any one of claims 7 to 9, characterized in that the light entrance surface and/or the light exit surface of two or more of the sintered bodies are integrally formed so as to be positioned on approximately the same plane.